Ceramaximin A and B, two bromotyrosine derivatives from the worm snail Ceraesignum maximum and their cytotoxic activity.

Two previously undescribed bromotyrosine derivatives, ceramaximins A and B (1‒2), together with six known compounds (3‒8), were isolated from the worm snail Ceraesignum maximum. The structures of the new metabolites were elucidated via comprehensive spectroscopic analyses, including HRESIMS and NMR experiments, while their absolute configurations were established by comparison of experimental and TDDFT-calculated ECD spectra. A plausible biosynthetic pathway for two new compounds was proposed. Compounds 1 and 2 exhibited moderate cytotoxic activity against HepG2, HeLa, and MCF-7 human cancer cell lines, with IC50 values ranging from 31.98 to 51.39 µM. Notably, this work represents the first phytochemical investigation of C. maximum.